Some forces are called contact forces because they require objects to touch. One is tension force, found in stretched wires. Another is the force found in a spring. And last are resistive forces: ...

Forgive me for all the posts on ESPN's Sport Science (example: Pulling and Power). I can't help myself. In the short episode recently, Sport Science compared a football player pulling a sled with huge ...

Friction is the force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor, friction makes this difficult. Friction ...